Re: Heat vs IR

[tom@xxxxxxxxxxxxxxxxxxxxxx (Tom Benedict)]

ARGH!  I *KNEW* this would happen.  Every time I try to give a
detailed answer to a question, I catch flak for stepping outside the
bounds of the photographic context (take the whole discussion on IR
polarizers).  Whenever I try to give a short explanation for
something, my reply gets tagged as being wrong.

I *know* heat is energy.  *Yes*, any blackbody emits at all
wavelengths to some extent.  *Yes* you can use a Planck function to
model how much a blackbody at a particular temperature will emit at a
particular wavelength.  *Yes*, I could go into a whole discussion on
wavelength-dependent opacities and the changes that makes to the
effective temperature of a blackbody.

I don't think that's what the person was asking, though.

I was trying to give a workable range for thermal IR as opposed to
"what I can capture on HIE film" IR.  For the most part you can't
capture thermal IR on HIE film (YES I KNOW ABOUT PHOTOGRAPHING HOT
IRONS).  For those wavelengths a cooled detector is typically used.
For wavelengths between around 0.650um and 1um, Kodak HIE works just
fine.

Tom


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Topic No. 7